This invention relates generally to firearms and, more particularly, to methods and devices for converting older or obsolete firearms for use with cartridge ammunition.
Cartridge ammunition, wherein the propellant (powder), ignition device (primer) and projectile (bullet) are integrated into a single, easily handled cartridge, represented a major step forward in the development of firearms. Prior to that time, the powder and bullet or ball were loaded separately, as was a percussion cap used to ignite the powder. Loading was a tedious process that took considerable time. Additionally, the black powder in use at that time necessitated a rough cleaning before each loading and a thorough cleaning after each period of use. Accordingly, loading and cleaning a black powder firearm was a complicated, time-consuming affair. The advent of cartridge ammunition not only greatly simplified to loading process, but the later development of "smokeless" powders largely reduced the need for meticulous cleaning after each use. The development of cartridge ammunition, therefore, was a major advancement in firearms development.
Despite the advancement represented by cartridge ammunition, many original and replica firearms designed for non-cartridge operation remain in use today. Some enthusiasts enjoy the history and romance associated with firearms of the past, while others participate in historical recreations and the like that require the use of period firearms. Still others, who are engaged in the business of making movies, (e.g., "westerns") or producing plays, need firearms that are true to the time in appearance. For all these reasons, firearms that are clearly "obsolete" in terms of technical development remain firmly in use today well over a century after they were originally designed. Additionally, a thriving market exists for modern reproductions of these old designs as well.
Despite the popularity of old firearm designs, the original problems that led to the development of cartridge ammunition still remain. "Black powder" arms are still difficult and time consuming to load and still require thorough cleaning after use. Although having to deal with these difficulties is often what creates the appeal, there are definitely times when the disadvantages of black powder are a hindrance or nuisance and the benefits of cartridge ammunition are desired, even by those who relish the past.
Various attempts have been made to convert black powder firearms to use with cartridge ammunition. In the case of black powder "cap and ball" revolvers, these attempts have centered around replacing the original cylinder with one chambered for a compatible cartridge. In one approach, such as that shown and described in U.S. Pat. No. 3,757,448 to Petrucci, a conversion cylinder is provided that is arranged to accept center-fire cartridge ammunition. As disclosed in that patent, "The chamber arrangement in the cylinder . . . will have to be identical to the original cylinder." The approach taken by Petrucci is effective provided there is sufficient clearance in the conversion cylinder for the replacement cartridge ammunition. This is not always the case.
For example, as 44 cal. cap and ball revolvers and 45 Long Colt ammunition both share the same bullet or ball diameter, it is natural to seek to adapt a 44 cal. cap and ball revolver to use 45 Long Colt cartridge ammunition. When this is done using prior techniques, however, it is found that, because the cartridge dimensions of the 45 Long Colt exceed the chamber dimensions of the 44 cap and ball revolver, it is not possible to orient six 45 Long Colt cartridges in precisely the same position and spacing as the chambers in the 44 cap and ball revolver. In particular, the rim diameter of the 45 Long Colt is sufficiently great that the rims of six 45 Long Colt cartridges would interfere with each other if all six cartridges were oriented and spaced as in a 44 cap and ball revolver. Accordingly, the approach taken by Petrucci is ineffective in converting a 44 cal. cap and ball revolver to use with 45 Long Colt ammunition.
To solve this problem, past efforts have provided replacement cylinders that chamber only five 45 Long Colt cartridges rather than six. By eliminating one of the chambers, more room is available in the cylinder and the interference problem with the cartridge rims is avoided. However, the reduction in shot capacity is significant when historical accuracy is to be preserved and when the time-tested safety practice of keeping the hammer down on an empty chamber is followed, regardless of whether cartridge ammunition is being used.
In view of the foregoing, a need exists for an apparatus and method that enables modern cartridge ammunition to be used in firearms not originally designed for such use, without changing the appearance or essential operating characteristics of the firearm.